The invention relates to a method for producing a sliding bearing composite material that has a support layer, in particular made of steel, a bearing metal layer made of a lead-free aluminum base alloy containing magnesium, and a running layer. The invention further relates to such a sliding bearing composite material and a sliding bearing element manufactured from same.
Sliding bearing composite materials of this type are known. Typical applications are found in the field of automotive engineering, typically in the area related to internal combustion engines, for example in the manufacture of crankshaft bearing shells and/or connecting rod bearing shells.
Typical sliding bearing composite materials have a support layer made of steel which ensures the mechanical stability and dimensional stability of the sliding bearing composite material. A bearing metal layer is typically applied to the support layer, in particular sintered, cladded, or cast onto the support layer. A running layer is often provided on the bearing metal layer. During use of the sliding bearing, the running layer of a sliding bearing element, which is made of the sliding bearing composite material and shaped in a bending-rolling process, is in contact with a sliding partner.
WO 2010/125026 A1 discloses a sliding bearing composite material of the type mentioned at the outset. For providing the bearing metal layer, it is proposed to use a hardenable aluminum base alloy having a comparatively high copper content of 3.5 to 4.5% by weight copper and 0.1 to 1.5% by weight magnesium in order to achieve a preferred hardness of 70 to 110 HV 0.01 (Vickers hardness). This is achievable due to the high copper content and presumably, solution annealing at high temperatures and subsequent quenching. The bearing metal layer as well as a running layer applied thereto are roll-cladded and have a corresponding thickness.
EP 0 672 840 A1 discloses application of an aluminum-tin-based running layer, exposed to the sliding partner, by roll cladding onto a bearing metal layer; AlZn4SiPb, AlZn4.5Mg, AISi11CuMgNi, and AlMgSi1 are mentioned. The roll-cladded composite thus obtained is rolled onto a support layer made of steel in a subsequent roll cladding step. For this sliding bearing composite material, in which the hardenable aluminum alloy had a hardness of 60 HV 0.5, the problem was observed that this layer was axially pressed out of the bearing point under heavy load. This problem was addressed in above-cited WO 2010/125026 A1 by further hardening by alloying with large quantities of copper.